There are a wide variety of remote-control model toys such as airplanes, race cars, beach cars, speed boats, etc. Because they are a small copy of the real object, they have high fidelity and use engines as the source of power. With high speed and a small size that makes easy for storage, they are widely popular.
However, before use, their fuel oil tank 10 must be filed in full as shown in FIG. 1. The connections between the engine 30 and fuel oil tank 10 of a remote-control model toy comprises an air duct 11 of fuel oil tank 10 connected to an air conduit 12 on the pressure port 21 of muffler 20. When the engine 30 starts running, the exhaust passes into fuel muffler 20, and a portion of the exhaust will be discharged into fuel oil tank 10 by means of pressure port 21 through air duct 12 and air conduit 11 to increase the pressure therein. Pressurized fuel oil in the auxiliary tank 10 will flow into a carburetor 31 by means of fuel oil intake 310 of the engine 30 from the fuel oil inlet 13 through fuel oil tube 14. Such design increases force against the fuel oil in the fuel oil tank 10 when the carburetor 31 is in action, whereby the gas discharged by the engine 30 from the muffler 20 into the fuel oil tank 10 may help deliver fuel oil into the carburetor 31 so as to make up for insufficient suction force of the carburetor 31. Using exhaust pressure to substitute for an "oil pump" function, not only reduces the size and weight but also lowers production costs. For filling the fuel oil tank 10, the fuel oil tube 14 has to be withdrawn from the fuel oil intake 30 of the carburetor 31, and a fuel oil bottle 80 is used for sucking fuel oil from the fuel oil drum 81. Fuel oil can be gradually fed through the fuel oil tube 14 by squeezing fuel oil bottle 80. Fueling in such a way is slow and causes waste of time. Further, fuel oil might leak out when the fuel oil bottle 80 is sucking fuel oil or delivering fuel oil so that it may cause waste of fuel oil and pollution on the user's hand. Because the fuel oil tank 10 cannot be observed, the user cannot discover if the fuel oil tank is full until fuel oil often flows into the muffler 20 through conduit 12. Therefore, it has the following defects:
1. When fuel oil overflows through the air conduit 12, fuel oil in the fuel oil tank 10 has flowed into the muffler 20 through pressure port 21 and air conduit 12 to cause the waste of fuel oil.
2. Because the combustion point of fuel oil is low, fuel oil leaked into the muffler 20 has the risk of ignition owing to the rising temperature of the muffler 20.
3. When overflow fuel oil flows back to the cylinder of the engine 30 from the muffler 20, the spark plug will become wet making the engine 30 difficult to start.
4. Upon completion of fueling, fuel accumulated in the engine 30 cylinder must be cleared away in order to start the engine smoothly. If not cleared away, residual fuel oil will result in "hydraulic compression" due to excess of fuel oil in the piston when mixing with air in the compression cylinder.
Because compression of fuel oil is limited, the piston will be stuck in the cylinder. Forcibly moving the piston may cause the piston links to be bent and damaged.